Hi guys,

Here's a challenge I hope you can help me solve.

Say I have a table of values with X and Y headers and a 3 x 3 array
hoding parameters that are a function of X and Y, call these f (X, Y)
as below.

Y
0.1 0.2 0.3
1 10 15 20
X 2 15 20 30
3 20 30 40

Say I am given a value of Y = 0.2 and the outcome of the X and Y, f
(X, Y) of 20, and the formula needs to return the value of X.

From the table above the result I would want to extract is X = 2. The
formula needs to look down the second column (Y=0.2) until it finds f
(X,Y) = 20. Sounds easy but I'm struggling. I generally use tables
where X and Y are known and the value of f(X, Y) is required, but I am
finding this trickier.

Please assume the values are always exact matches. I may require
bilinear interpolation if the numbers are not exact - but I can do
that myself.

Any suggestions are greatly appreciated.

Thanks
Edu